A timepiece of this type is for example described in patent application EP 1 513 031. In this example, the two cases pivot relative to each other around a pivot axis substantially perpendicular to the plane of the cases, so that the two cases slide one on the other when they are moved. In this way, the upper case is pivoted relative to the lower case to reveal at least part of the front face thereof. The drawback of such a construction is that the lower case still remains at least partially hidden by the upper case. This requires that the display means be positioned on the lower case eccentrically so that they are still visible, and therefore that specific pieces be provided. The information is sent from one case to the other via an arbor rotating around an axis combined with that of the hinge. With such a configuration, the rotational movement of one of the cases relative to the other is of the same type as the control movement. This involves a complex mechanism to guarantee the transmission of information despite this relative movement, or an interruption of the kinematic connection, as proposed by the mechanism mentioned above.
Also known is a timepiece as described in patent application EP 1 840 678, comprising a first watch case reversible according to two service positions, containing a clockwork movement, a second watch case comprising an additional mechanism, and a control device by mechanical impulses contained in the first watch case. More particularly, the elements of this control device are arranged in the space between the two cases, in which space dust can become lodged, which can harm the operation of the piece. Moreover, the device comprises a lever ensuring the transmission between the two cases, the lever being positioned in a groove of the cradle in which the additional mechanism is mounted. This means that outside the two service positions, i.e. when the case is open and is not superimposed on the second case, the lever no longer cooperates with the movement and the transmission of the information from the movement to the additional module is no longer ensured. It is therefore required for the first case to be in one of its service positions at midnight, when the movement provides an impulse to the date module. If the first case is in an open position relative to the second case, the update does not occur. Moreover, the transmission of information at a frequency greater than once a day could lead to serious lags, detrimental to the precision of the additional mechanism.
One aim of the present invention is therefore to offset these drawbacks, by proposing a timepiece in which the information is always transmitted from one part of the movement to the other, regardless of the position of the cases relative to each other.